Separation media slurry tank

ABSTRACT

A tank adapted to be used for suspending separation media slurry before transferring the separation media slurry to a column or a container comprises:
         an impeller ( 7 ) adapted to rotate in order to mix the media slurry,   a nozzle ( 9 ) provided protruding into the tank from the bottom ( 8 ) thereof, and   an adjustable pipe ( 5 ) having an open end ( 6 ) positioned in the tank and which can be adjusted in position. The nozzle ( 9 ) and the adjustable pipe ( 5 ) are adapted to be connected to a pump ( 3 ) adapted to pump liquid from the adjustable pipe ( 5 ) when the open end ( 6 ) of the adjustable pipe ( 5 ) has been positioned in an uppermost liquid phase provided in the tank when the media slurry has started to sediment and pump the liquid, possibly containing a small amount of media, through the nozzle ( 9 ) back into the tank from the tank bottom ( 8 ) in order to start re-suspending media that has sedimented in the tank.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a filing under 35 U.S.C. §371 and claims priority tointernational patent application number PCT/SE2007/001125 filed Dec. 18,2007, published on Jul. 10, 2008, as WO 2008/082339, which claimspriority to patent application number 0700014-4 filed in Sweden on Jan.2, 2007.

FIELD OF THE INVENTION

The present invention relates to a method and a tank for suspendingseparation media slurry before transferring the slurry to a column orcontainer.

BACKGROUND OF THE INVENTION

Separation media could be for example chromatography media and densitygradient media. The media could be for example resins based on naturalor synthetic polymer particles or inorganic material. For chromatographythe separation media needs to be provided into a chromatography column.For the transportation of the separation media into for example a columnthe media needs first to be suspended into an homogenous media slurrymixture. The separation media is normally suspended with a liquid, forexample water, buffer or a solvent. This suspended media is usuallycalled media slurry. When a column should be filled with media slurryfrom a storage container, an intermediate tank is used where the slurryis mixed into a homogenous mixture. The media slurry is often stirredmanually in the tank and it is important that the media slurry becomes ahomogenous mixture regarding the distribution of different sizes ofparticles in the media. Of course it is not convenient to stir manuallyespecially when there is a large amount of media slurry to be stirred.It could also take quite a long time to fill the column with the mediaslurry and the media slurry needs to be stirred the whole time. Anotherway to mix the slurry that is sometimes used is to shake or tilt thetank back and forth. This could be advantageous for small tanks andsmall volumes of slurry but is hard to perform and not suitable for big,heavy tanks.

Solutions have been proposed, for example in EP0515955 or JP4323557,where permanent, electrical stirrers, also called impellers are used.There are however different problems associated with these kind ofimpellers. If the impeller is not running the whole time when the mediaslurry is inside the tank the slurry will sediment and then it will behard to start the impeller in the sedimented media. This requiresfurthermore an oversized engine. When starting the impeller insedimented media the media particles can be damaged because of shearforces provided by the impeller. It could be preferable to not run theimpeller the whole time in order to minimize possible damage to theparticles caused by the impeller.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an improved method andtank for suspending separation media slurry before transportation ofsaid media slurry into for example a column where particles in saidmedia are not damaged.

This is achieved in a method according to claim 1 and in a tankaccording to claim 3 and in a tank system according to claim 7.

Hereby the impeller does not need to start in a thick, sedimented mediawith the risk of damaging particles in the media and the impeller doesnot need to be running the whole time when the separation media isinside the tank. The spraying of liquid by the nozzle starts there-suspension of the media from the bottom of the tank and the impellercan be started when the media has been sufficiently re-suspended.Furthermore liquid from the liquid phase of the media slurry havingstarted to sediment is used for the spraying by the nozzle and hereby nonew liquid need to be added and hereby the slurry concentration can bekept constant.

Further suitable embodiments are described in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a separation media slurry tank accordingto the invention.

FIG. 2 is a flow chart describing the steps of the method.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a schematic view of a separation media slurry tank 1 accordingto the invention. If media is to be fed to a column from a media storagecontainer the media is first transferred from the storage container to amedia tank according to the invention. This could be done by connectinga tube from the storage container to a pump 3 provided in connectionwith the media slurry tank. Said pump is further connected to anadjustable pipe 5 that has an open end 6 provided inside the tank 1.Said adjustable pipe 5 is further described below. Hereby the mediaslurry can be pumped from the media storage container to the tank.Alternatively the media could be transferred from the storage containerto the tank using another pump and some other tubes or pipes.

When the media has been transferred to the tank it immediately starts tosediment. An impeller 7 that is provided inside the tank can be startedfrom the beginning and keep on stirring the media slurry the whole timeuntil the media has been transferred to a column where it should be usedfor, for example chromatography, but according to the invention, as willbe further described below, the impeller does not need to be ongoing thewhole time. The impeller 7 is preferably designed as a coil in theheight direction of the tank, this kind of impeller is also called ahelical ribbon. Other designs such as a two- or three-bladed propelleror an impeller formed as an anchor are however also possible. In FIG. 1a two-bladed propeller 7 is shown. Furthermore the impeller is suitablyprovided with its lowest end close to the bottom 8 of the tank.

According to the invention a nozzle 9 is furthermore provided protrudinginto the tank from the bottom 8 of the tank. This nozzle is connected tothe pump 3, which in turn is connected to the adjustable pipe 5 asdescribed above. The adjustable pipe 5 can be adjusted to have its openend 6 in a liquid phase provided above the sedimented media as soon asthe media slurry is starting to sediment. According to the invention thepump 3 pumps liquid from the liquid phase, through the adjustable pipe 5and further to the nozzle 9. The pump applies a pressure to the liquidin the nozzle and the nozzle is designed such that the liquid isintroduced with some speed, such as spraying, into the sedimented mediafrom the bottom 8 of the tank. This has the advantage that thesedimented media in the tank will start to re-suspend. Preferably theimpeller is not started until the sedimented media has been sufficientlyre-suspended by the spraying from the nozzle. Hereby it will be easierto start the impeller than it would have been if the impeller would haveto start inside thick, sedimented media and the risk for damagingparticles of the media is minimized. Furthermore the use of the liquidfrom the liquid phase of the sedimented media slurry for the spraying bythe nozzle implies that no extra liquid need to be provided and themedia slurry concentration can be kept constant.

When the media slurry has been stirred and mixed enough it can betransferred to a column through a pipe 11 from the bottom of the tank 1.

The tank according to the invention can also be used when transferringmedia from a column to a storage container. It could be suitable tofirst transfer the media to the tank, suspend the media sufficientlyaccording to what was previously described and then transfer the mediaslurry to the storage container.

The method according to one embodiment of the invention where mediaslurry is transferred from a storage container to a column via the tankwill now be further described with reference to the flowchart in FIG. 2.The steps are described in order below.

S1: Media slurry is first transferred from the storage container to thetank according to the invention. This could be done by using a pump anda tube or pipe. Possibly a pump 3 connected to the tank and theadjustable pipe 5 of the tank can be used for this transferring of mediaslurry from the storage container to the tank. As soon as the mediaslurry has entered the tank it starts to sediment—actually it is alreadysedimented to some degree since no stirring has been performed in thestorage container, i.e. media will sediment at the bottom 8 of the tankand a liquid phase (possibly containing some particles also) will bebuilt up over the sedimented media.

The method steps S2-S11 need not to be performed immediately aftertransferring of the media slurry to the tank. But when it is time forthe transferring of the media slurry to the column the media slurryneeds to be mixed into an homogenous media slurry and then the stepsS2-S11 will be performed.

S2: The adjustable pipe 5 is adjusted such that its open end 6 is in theliquid phase in the tank.

S3: The next step is to pump liquid from the liquid phase through theadjustable pipe 5 by using the pump 3.

S5: The liquid is then transported through the pump 3 to the nozzle 9.

S7: By applying a pressure to the nozzle 9 from the pump 3 the liquid issprayed out from the nozzle 9 from the bottom (8) of the tank into thesedimented media.

S9: When the sedimented media close to the bottom 8 of the tank has beensufficiently re-suspended the impeller 7 is started. The impeller 7 isdriven until a homogenous mixture of the media slurry is achieved.

S11: When the media slurry is sufficiently mixed it is transferred tothe column. If the method according to the invention should be appliedfor the invert transferring of media slurry, i.e. from column to storagecontainer the same steps S1-S11 are followed with the only change thatthe storage container replaces the column and the column replaces thestorage container.

The above embodiments are to be understood as illustrative examples ofthe invention. Further embodiments of the invention are envisaged. It isto be understood that any feature described in relation to any oneembodiment may be used alone, or in combination with other featuresdescribed, and may also be used in combination with one or more featuresof any other of the embodiments, or any combination of any other of theembodiments. Furthermore, equivalents and modifications not describedabove may also be employed without departing from the scope of theinvention, which is defined in the accompanying claims.

1. A method for suspending separation media slurry in a tank, beforetransferring the separation media slurry to a column or a container,comprising the steps of: pumping liquid from an uppermost liquid phasebeing formed in the tank when the media slurry is sedimenting, saidliquid possibly containing a small amount of media but is hereafterbeing called liquid; transferring said liquid to a nozzle (9) protrudinginto said tank from the bottom (8) of the tank; applying a pressure tosaid nozzle (9) such that said liquid is sprayed out from the nozzle (9)into the sedimented media in the tank and thereby the sedimented mediastarts to re-suspend; starting an impeller (7) provided in the tank inorder to stir said media slurry that already has started to re-suspend.2. The method of claim 1, further comprising adjusting the height of anopen end (6) of an adjustable pipe (5) provided inside the tank, theheight being adjusted to the liquid phase of the media slurry havingstarted to sediment, said adjustable pipe (5) being connected to saidnozzle (9) through a pump (3).
 3. A tank adapted to be used forsuspending separation media slurry before transferring the separationmedia slurry to a column or a container, said tank comprising: animpeller (7) adapted to rotate in order to mix the media slurry, anozzle (9) provided protruding into the tank from the bottom (8) of thetank, and an adjustable pipe (5) having an open end (6) positioned inthe tank, said open end being possible to adjust in position, saidnozzle (9) and said adjustable pipe (5) being adapted to be connected toa pump (3) which is adapted to pump liquid from the adjustable pipe (5)when said open end (6) of the adjustable pipe (5) has been positioned inan uppermost liquid phase provided in the tank when the media slurry hasstarted to sediment and pump said liquid, possibly containing a smallamount of media but hereafter being called liquid, through said nozzle(9) back into the tank from the bottom (8) of the tank in order to startto re-suspend media that has sedimented in the tank.
 4. The tank ofclaim 3, wherein said impeller (7) is adapted to start after thesedimented media has started to re-suspend by the introducing of theliquid from the nozzle.
 5. The tank of claim 3, wherein the impeller (7)is provided close to the bottom (8) of the tank.
 6. The tank of claim 3,wherein the impeller (7) is designed as a coil in the height directionof the tank.
 7. A tank system comprising the tank of claim 3 and a pump(3) connected to the adjustable pipe (5) and to the nozzle (9).